Propylene polymer compositions and uses thereof

ABSTRACT

The present invention provides a propylene polymer composition having excellent transparency, flexibility, heat resistance, scratch resistance and rubber elasticity with a good balance. The propylene polymer composition comprises 1 to 40 parts by weight of isotactic polypropylene (i) and 60 to 99 parts by weight of a propylene/ethylene/α-olefin copolymer (ii) which contains 45 to 89% by mol of a propylene component, 10 to 25% by mol of an ethylene component, and optionally, 0 to 30% by mol of constituent units (a) derived from an α-olefin of 4 to 20 carbon atoms.

FIELD OF THE INVENTION

The present invention relates to propylene polymer compositions, andmore particularly to propylene polymer compositions having excellenttransparency, flexibility, scratch resistance, heat resistance andrubber elasticity.

BACKGROUND OF THE INVENTION

Because polypropylene is inexpensive and has excellent rigidity,moisture resistance and heat resistance, it has been widely used as anautomotive material, a household electric appliance material, etc. Onthe other hand, a tendency to get rid of non-rigid PVC is strengthenedin view of problems of environmental hormones, dioxin and the like, andpolyolefins having flexibility and transparency have been desired. Insuch circumstances, thermoplastic polyolefin elastomers called TPO haveno transparency though they have excellent flexibility, and systemsobtained by adding styrene elastomers to PP (e.g., Japanese PatentLaid-Open Publication No. 048485/1995) are expensive though they haveflexibility and transparency, so that uses thereof are restricted.

DISCLOSURE OF THE INVENTION

The present invention is intended to solve such problems associated withthe prior art as described above, and it is an object of the presentinvention to provide a propylene polymer composition which isinexpensive and has excellent transparency, flexibility, heatresistance, scratch resistance and rubber elasticity with a goodbalance.

The propylene polymer composition containing no styrene or ethyleneblock copolymer according to the present invention satisfies thefollowing requirements (A), (B), (C) and (D) at the same time:

(A) in a dynamic viscoelasticity measurement (10 rad/s) in a torsionmode, a peak of loss tangent (tan δ) is present in the range of −25° C.to 25° C., and its value is not less than 0.5,

(B) a ratio of a storage elastic modulus G′ (20° C.) to a storageelastic modulus G′ (100° C.) obtained from the above dynamicviscoelasticity measurement, G′ (20° C.)/G′ (100° C.), is not more than5,

(C) a penetration temperature (° C.), as measured in accordance with JISK7196, is in the range of 100° C. to 168° C., and

(D) a residual strain measured after the lapse of 10 minutes fromunloading, said unloading being performed after a 100% strain is givenunder the conditions of a chuck distance of 30 mm and a pulling rate of30 mm/min and kept for 10 minutes, is not more than 20%.

The propylene polymer composition according to the present inventioncomprises 1 to 40 parts by weight of isotactic polypropylene (i) and 60to 99 parts by weight of a propylene/ethylene/α-olefin copolymer (ii)which contains 45 to 89% by mol of a propylene component, 10 to 25% bymol of an ethylene component, and optionally, 0 to 30% by mol ofconstituent units (a) derived from an α-olefin of 4 to 20 carbon atoms(the amount of at least one of the ethylene component and theconstituent units (a) derived from an α-olefin of 4 to 20 carbon atomsis not 0% by mol), and has a tensile modulus (YM), as measured inaccordance with JIS 6301, of not more than 100 MPa.

In a preferred embodiment of the present invention, the constituent unit(a) derived from an α-olefin of 4 to 20 carbon atoms is 1-butene and/or1-octene.

The propylene polymer composition according to the present invention hasexcellent transparency, flexibility, heat resistance, scratch resistanceand rubber elasticity with a good balance.

PREFERRED EMBODIMENTS OF THE INVENTION

The propylene polymer composition according to the present invention isdescribed in detail hereinafter. First, the components (i) and (ii)contained in the propylene polymer composition are described.

Isotactic Polypropylene (i)

In the present invention, a specific propylene polymer having thefollowing properties is employed. The propylene polymer may behomopolypropylene or a propylene/α-olefin random polymer or a propyleneblock copolymer, with the proviso that it has the following properties.However, preferable is homopolypropylene or a propylene/α-olefin randomcopolymer.

The isotactic polypropylene (i) for use in the present invention has amelt flow rate (MFR, ASTM D 1238, 230° C., under a load of 2.16 kg) of0.01 to 400 g/10 min, preferably 0.5 to 90 g/10 min, and has a meltingpoint, as measured by DSC, of not lower than 120° C., preferably notlower than 130° C., more preferably not lower than 150° C.

From the isotactic polypropylene (i) having such a MFR value, apropylene polymer composition having excellent flowability and capableof being molded into a large article is obtained. A composition preparedfrom isotactic polypropylene having a MFR value exceeding 400 g/10 minsometimes has poor impact resistance (Izod impact strength).

When the isotactic polypropylene (i) is a propylene/α-olefin randomcopolymer, the α-olefin is preferably selected from ethylene and/orα-olefins of 4 to 20 carbon atoms, and such ethylene and/or α-olefin isdesirably contained in an amount of 0.3 to 7% by mol, preferably 0.3 to6% by mol, more preferably 0.3 to 5% by mol.

A content of a room temperature n-decane soluble component in apropylene polymer can be determined by immersing 5 g of a sample(propylene polymer) in 200 cc of boiling n-decane for 5 hours todissolve the sample, then cooling the solution to room temperature,filtering off a precipitated solid phase through a G4 glass filter, thendrying the solid phase, measuring a weight of the solid phase andcounting back the content of the n-decane soluble component from theweight of the solid phase.

The isotactic polypropylene (i) for use in the present invention can beprepared by various processes, and for example, it can be prepared bythe use of a stereospecific catalyst. More specifically, it can beprepared by the use of a catalyst formed from a solid titanium catalystcomponent, an organometallic compound catalyst component, and ifnecessary, an electron donor. The solid titanium catalyst component is,for example, a solid titanium catalyst component in which titaniumtrichloride or a titanium trichloride composition is supported on acarrier having a specific surface area of not less than 100 m²/g or asolid titanium catalyst component which contains magnesium, halogen, anelectron donor (preferably an aromatic carboxylic acid ester or an alkylgroup-containing ether) and titanium as essential components and inwhich these essential components are supported on a carrier having aspecific surface area of not less than 100 m²/g. The isotacticpolypropylene can be prepared also by the use of a metallocene catalyst.Of these, the latter solid titanium catalyst component is preferable.

As the organometallic compound catalyst component, an oragnoaluminumcompound is preferable. Examples of the organoaluminum compounds includetrialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide andalkylaluminum dihalide. The organoaluminum compound can be properlyselected according to the type of the titanium catalyst component used.

As the electron donor, an organic compound having a nitrogen atom, aphosphorus atom, a sulfur atom, a silicon atom, a boron atom or the likeis employable, and preferable is an ester compound or an ether compoundhaving such an atom.

The catalyst may be activated by a means such as copulverization, andmay be a catalyst onto which such an olefin as previously described hasbeen prepolymerized.

Propylene/ethylene/α-olefin Random Copolymer (ii)

The propylene/ethylene/α-olefin random copolymer contains a propylenecomponent in an amount of 45 to 89% by mol, preferably 45 to 80% by mol,more preferably 50 to 75% by mol, an ethylene component in an amount of10 to 25% by mol, preferably 10 to 23% by mol, more preferably 12 to 23%by mol, and if necessary, constituent units (a) derived from an α-olefinof 4 to 20 carbon atoms in an amount of 0 to 30% by mol, preferably 0 to25% by mol, more preferably 0 to 20% by mol.

The propylene/ethylene/α-olefin random copolymer (ii) containing apropylene component, an ethylene component, and if necessary, anα-olefin component of 4 to 20 carbon atoms in the above amounts exhibitsexcellent compatibility with the isotactic polypropylene, and theresulting propylene polymer composition tends to exhibit sufficienttransparency, flexibility, heat resistance and scratch resistance.

The propylene/ethylene/α-olefin random copolymer (ii) desirably has anintrinsic viscosity [η], as measured in decalin at 135° C., of usually0.01 to 10 dl/g, preferably 0.05 to 10 dl/g. When the intrinsicviscosity [η] of the propylene/ethylene/α-olefin random copolymer (ii)is in the above range, this propylene/ethylene/α-olefin random copolymeris excellent in properties such as weathering resistance, ozoneresistance, thermal aging resistance, low-temperature characteristicsand dynamic fatigue resistance.

The propylene/ethylene/α-olefin random copolymer (ii) has a stress(M100) at 100% strain, as measured in accordance with JIS K6301 using aJIS No. 3 dumbbell under the conditions of a span of 30 mm, a pullingrate of 30 mm/min and a temperature of 23° C., of not more than 4 MPa,preferably not more than 3 MPa, more preferably not more than 2 Mpa.When the stress is in this range, the propylene/ethylene/α-olefin-randomcopolymer (ii) exhibits excellent flexibility, transparency and rubberelasticity.

The propylene/ethylene/α-olefin random copolymer (ii) has acrystallinity, as measured by X-ray diffractometry, of not more than20%, preferably 0 to 15%. Further, the propylene/ethylene/α-olefinrandom copolymer (ii) has a single glass transition temperature, and theglass transition temperature Tg, as measured by a differential scanningcalorimeter (DSC), is desirable to be usually not higher than −10° C.,preferably not higher than −15° C. When the glass transition temperatureTg of the propylene/ethylene/α-olefin random copolymer (ii) is in theabove range, the copolymer (ii) exhibits excellent low-temperatureresistance and low-temperature characteristics.

In the case where a melting point (Tm, ° C.) is present in anendothermic curve of the propylene/ethylene/α-olefin random copolymer(ii) measured by a differential scanning calorimeter (DSC), the quantityof heat of fusion ΔH is not more than 30 J/g, and a C3 content (% bymol) and the quantity of heat of fusion ΔH (J/g) satisfy the followingrelationship:ΔH<345 Ln (C3 content (% by mol))−1492,with the proviso that the C3 content satisfies the condition of 76≦C3content (% by mol)≦90.

The propylene/ethylene/α-olefin random copolymer (ii) desirably has amolecular weight distribution (Mw/Mn, in terms of polystyrene, Mw:weight-average molecular weight, Mn: number-average molecular weight),as measured by GPC, of not more than 4.0, preferably not more than 3.0,more preferably not more than 2.5.

The propylene/ethylene/α-olefin random copolymer (ii) may be a copolymera part of which has been graft modified with a polar monomer. Examplesof the polar monomers include a hydroxyl group-containing ethylenicallyunsaturated compound, an amino group-containing ethylenicallyunsaturated compound, an epoxy group-containing ethylenicallyunsaturated compound, an aromatic vinyl compound, an unsaturatedcarboxylic acid or its derivatives, a vinyl ester compound and vinylchloride.

The modified propylene/ethylene/α-olefin copolymer is obtained by graftpolymerization of the propylene/ethylene/α-olefin random copolymer (ii)with the polar monomer. In the graft polymerization of thepropylene/ethylene/α-olefin random copolymer (ii) with the polarmonomer, the polar monomer is used in an amount of usually 1 to 100parts by weight, preferably 5 to 80 parts by weight, based on 100 partsby weight of the propylene/ethylene/α-olefin random copolymer (ii). Thegraft polymerization is usually carried out in the presence of a radicalinitiator.

As the radical initiator, an organic peroxide, an azo compound or thelike is employable.

The radical initiator can be used by mixing it as it is with thepropylene/ethylene/α-olefin copolymer (ii) and the polar monomer, but itcan be used after it is dissolved in a small amount of an organicsolvent. As the organic solvent, any of organic solvents capable ofdissolving the radical initiator can be used without specificrestriction.

In the graft polymerization of the propylene/ethylene/α-olefin copolymer(ii) with the polar monomer, a reducing substance may be used. By theuse of the reducing substance, the degree of grafting of the polarmonomer can be increased.

The graft modification of the propylene/ethylene/α-olefin copolymer (ii)with the polar monomer can be carried out by a hitherto known method.For example, the graft modification can be carried out by dissolving thepropylene/ethylene/α-olefin copolymer (ii) in an organic solvent, thenadding a polar monomer, a radical initiator, etc. to the solution, andreacting them at a temperature of 70 to 200° C., preferably 80 to 190°C., for 0.5 to 15 hours, preferably 1 to 10 hours.

Further, the modified propylene/ethylene/α-olefin copolymer can beprepared also by reacting the propylene/ethylene/α-olefin randomcopolymer (ii) with the polar monomer using an extruder or the like inthe absence of a solvent. It is desirable to carry out this reactionusually at a temperature of not lower than the melting point of thepropylene/ethylene/α-olefin copolymer (ii), specifically, a temperatureof 120 to 250° C., for a period of usually 0.5 to 10 minutes.

In the modified propylene/ethylene/α-olefin copolymer obtained as above,the degree of modification (degree of grafting of the polar monomer) isdesirable to be in the range of usually 0.1 to 50% by weight, preferably0.2 to 30% by weight, more preferably 0.2 to 10% by weight.

When the modified propylene/ethylene/α-olefin copolymer is contained inthe propylene polymer composition of the present invention, thecomposition exhibits excellent adhesion to other resins and excellentcompatibility with them, and moreover, wettability of a surface of amolded product obtained from the propylene polymer composition issometimes improved.

Preparation of propylene/ethylene/α-olefin Random Copolymer (ii)

The propylene/ethylene/α-olefin random copolymer (ii) for use in thepresent invention can be prepared using the aforesaid metallocenecatalyst for preparing the isotactic polypropylene (i) in the samemanner as described above, or can be prepared using a metallocenecatalyst, but the process employable is not limited thereto.

Styrene or Ethylene Block Copolymer

The styrene or ethylene block copolymer means an ethylene/α-olefin blockcopolymer (M) or an aromatic hydrocarbon block copolymer (N) describedbelow.

Ethylene/α-olefin Block Copolymer (M)

The ethylene/α-olefin block copolymer (M) that is not contained in thepropylene polymer composition of the present invention comprises alow-crystalline copolymer part and an amorphous copolymer part, said lowcrystalline copolymer part containing a crystalline polyethylene portionwhich comprises 5 to 40% by mol of constituent units derived from anolefin of 3 to 10 carbon atoms and 60 to 95% by mol of constituent unitsderived from ethylene.

Further, the ethylene/α-olefin block copolymer satisfies all thefollowing requirements (1) to (3):

(1) the melting point (Tm) obtained from an endothermic curve of DSC andthe ethylene content (C2) measured by a conventional NMR method satisfythe following relationship:Tm (° C.)>3.9×C2 (mol %)−230,

(2) the molecular weight distribution, as measured by GPC, is in therange of 1 to 1.5, and

(3) the quantity of a n-decane soluble component at room temperature isin the range of 0 to 20% by weight.

The quantity of the 23° C. n-decane soluble component in theethylene/α-olefin block copolymer is measured in the following manner.That is to say, in a 1-liter flask equipped with a stirrer, 3 g of apolymer sample, 20 mg of 2,6-di-tert-butyl-4-methylphenol and 500 ml ofn-decane are placed, and they are heated on an oil bath at 145° C. todissolve the polymer sample. After the polymer sample is dissolved, thesolution is cooled to room temperature over a period of about 8 hours,followed by holding the solution on a water bath at 23° C. for 8 hours.A polymer precipitated and the n-decane solution containing a dissolvedpolymer are separated from each other by filtration using a glass filterof G-4 (or G-2) The thus obtained solution is heated under theconditions of 10 mmHg and 150° C. to dry the polymer dissolved in then-decane solution until a constant weight is reached. This weight istaken as the quantity of the 23° C. decane soluble component. Thequantity of the 23° C. n-decane soluble component in theethylene/α-olefin block copolymer is calculated as a percentage based onthe weight of the polymer sample.

Examples of the olefins of 3 to 20 carbon atoms include propylene,1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene,1-octene, 3-methyl-1-butene, 1-decene, 1-dodecene, 1-tetradodecene,1-hexadecene, 1-octadecene, 1-eicosene, cyclopentene, cycloheptene,norbornene, 5-ethyl-2-norbornene, tetracyclododecene and2-ethyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene.

In the ethylene/α-olefin block copolymer, two or more kinds of theconstituents derived from the olefins of 3 to 20 carbon atoms andethylene may be contained.

In the ethylene/α-olefin block copolymer referred to herein, constituentunits derived from a diene compound of 4 to 20 carbon atoms may becontained in an amount of not more than 5% by mol.

Examples of such diene compounds include 1,3-butadiene, 1,3-pentadiene,1,4-pentadiene, 1,3-hexadiene, 1,4-hexadiene, 1,5-hexadiene,4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 6-methyl-1,6-octadiene,7-methyl-1,6-octadiene, 6-ethyl-1,6-octadiene, 6-propyl-1,6-octadiene,6-butyl-1,6-octadiene, 6-methyl-1,6-nonadiene, 7-methyl-1,6-nonadiene,6-ethyl-1,6-nonadiene, 7-ethyl-1,6-nonadiene, 6-methyl-1,6-decadiene,7-methyl-1,6-decadiene, 6-methyl-1,6-undecadiene, 1,7-octadiene,1,9-decadiene, isoprene, butadiene, ethylidenenorbornene,vinylnorbornene and dicyclopentadiene.

Preparation of the ethylene/α-olefin block copolymer (M) is describedin, for example, Japanese Patent Laid-Open Publication No. 043770/1993.

Aromatic Hydrocarbon Block Copolymer (N)

The aromatic hydrocarbon block copolymer (N) that is not contained inthe propylene polymer composition of the present invention is anaromatic vinyl/conjugated diene block copolymer (N1) comprising blockpolymerization units (X) derived from aromatic vinyl and blockpolymerization units (Y) derived from conjugated diene, or itshydrogenation product (N2).

The aromatic vinyl/conjugated diene block copolymer (N1) of such aconstitution is represented by, for example, X(YX)_(n) or (XY)_(n) (n isan integer of 1 or greater)

In such a styrene block copolymer, the aromatic vinyl blockpolymerization unit (X) that is a hard segment is present as acrosslinking point of the conjugated diene block polymerization unit (Y)and forms physical crosslinking (domain). The conjugated diene blockpolymerization unit (Y) present between the aromatic vinyl blockpolymerization units (X) is a soft segment and has rubber elasticity.

Examples of the aromatic vinyls for forming the block polymerizationunits (X) include styrene, and styrene derivatives, such asα-methylstyrene, 3-methylstyrene, p-methylstyrene, 4-propylstyrene,4-dodecylstyrene, 4-cyclohexylstyrene, 2-ethyl-4-benzylstyrene and4-(phenylbutyl)styrene. Examples of the conjugated dienes for formingthe block polymerization units (Y) include butadiene, isoprene,pentadiene, 2,3-dimethylbutadiene and combinations thereof. When theconjugated diene block polymerization units (Y) are derived frombutadiene and isoprene, the units derived from butadiene and isopreneare contained in amounts of not less than 40% by mol. The conjugateddiene block polymerization unit (Y) may be any of a randomcopolymerization unit, a block copolymerization unit and a taperedcopolymerization unit. The content of the aromatic vinyl polymerizationunits can be measured by a conventional method, such as infraredspectroscopy or NMR spectroscopy. The hydrogenation product (N2) of thearomatic vinyl/conjugated diene block copolymer can be obtained byhydrogenating the aromatic vinyl/conjugated diene block copolymer (N1)by a publicly known method. The hydrogenation. product (N2) of thearomatic vinyl/conjugated diene block copolymer usually has a degree ofhydrogenation of not less than 90%. This degree of hydrogenation is avalue given when the total amount of carbon-carbon double bonds in theconjugated diene block polymerization units (Y) is taken as 100%.

Propylene Polymer Composition

The propylene polymer composition containing no styrene or ethyleneblock copolymer according to the present invention satisfies thefollowing requirements (A), (B), (C) and (D) at the same time. Theexpression “containing no styrene or ethylene block copolymer” meansthat the content of a styrene or ethylene block copolymer in thepropylene polymer composition is not more than 10% by weight, preferablynot more than 5% by weight, more preferably not more than 2% by weight.

(A) In a dynamic viscoelasticity measurement (10 rad/s) in a torsionmode, a peak of loss tangent (tan δ) is present in the range of −25° C.to 25° C., and its value is not less than 0.5.

(B) A ratio of a storage elastic modulus G′ (20° C.) to a storageelastic modulus G′ (100° C.) obtained from the above dynamicviscoelasticity measurement, G′ (20° C.)/G′ (100° C.), is not more than5.

(C) A penetration temperature (° C.), as measured in accordance with JISK7196, is in the range of 100° C. to 168° C.

(D) A residual strain measured after the lapse of 10 minutes fromunloading, said unloading being performed after a 100% strain is givenunder the conditions of a chuck distance of 30 mm and a pulling rate of30 mm/min and kept for 10 minutes, is not more than 20%.

In the requirement (A), the loss tangent (tan δ) in the range of −25° C.to 25° C. is not less than 0.5, preferably 0.5 to 2.5, more preferably0.6 to 2. If the loss tangent (tan δ) in the range of −25° C. to 25° C.is less than 0.5, there is a tendency that flexibility cannot beexhibited sufficiently, or even if flexibility is exhibited, scratchresistance tends to be deteriorated.

In the requirement (B), the ratio of a storage elastic-modulus G′ (20°C.) to a storage elastic modulus G′ (100° C.), G′ (20° C.)/G′ (100° C.),is not more than 5, preferably not more than 4, more preferably not morethan 3.5. If the ratio of a storage elastic modulus G′ (20° C.) to astorage elastic modulus G′ (100° C.), G′ (20° C.)/G′ (100° C.), exceeds5, there is a tendency that surface tackiness occurs, handling isdeteriorated and sufficient heat resistance cannot be exhibited.

In the requirement (C), the penetration temperature (° C.), as measuredin accordance with JIS K7196, is in the range of 100° C. to 168° C.,preferably 120° C. to 168° C., more preferably 140° C. to 168° C. If thepenetration temperature is lower than 100° C., application for useswhere heat sterilization etc. is required becomes infeasible.

In the requirement (D), a residual strain measured in the followingmanner is not more than 20%, preferably not more than 18%, morepreferably not more than 16%. That is to say, to a dumbbell specimenhaving a length of 50 mm, a width of 5 mm and a thickness of 1 mm^(t), a100% strain is given under the conditions of a distance between markedlines of 30 mm and a pulling rate of 30 mm/min. The specimen is held inthis state for 10 minutes and then unloaded, and after the lapse of 10minutes from the unloading, a residual strain is measured. If theresidual strain exceeds 20%, rubber elasticity tends to be lowered, andhence, application for uses where elastic properties or restortionproperties are required becomes infeasible.

The propylene polymer composition having the above properties (A) to (D)comprises the isotactic polypropylene (i) in an amount of 1 to 40 partsby weight, preferably 1 to 30 parts by weight, more preferably 1 to 25parts by weight, and the propylene/ethylene/α-olefin copolymer (ii) inan amount of 60 to 99 parts by weight, preferably 70 to 99 parts byweight, more preferably 75 to 99 parts by weight, said copolymer (ii)containing 45 to 89% by mol of a propylene component, 10 to 25% by molof an ethylene component, and if necessary, 0 to 30% by mol ofconstituent units (a) derived from an α-olefin of 4 to 20 carbon atoms(the amount of at least one of the ethylene component and theconstituent units (a) derived from an α-olefin of 4 to 20 carbon atomsis not 0% by mol).

A molded product comprising the propylene polymer composition desirablyhas a haze, as measured in accordance with ASTM D 1003, of not more than25%, preferably not more than 20%.

A molded product comprising the propylene polymer composition desirablyhas a tensile modulus (YM), as measured in accordance with JIS 6301, ofnot more than 100 MPa, preferably not more than 80 MPa.

The propylene polymer composition of the present invention has a meltflow rate (ASTM D 1238, 230° C., load of 2.16 kg) of usually 0.0001 to1000 g/10 min, preferably 0.0001 to 900 g/10 min, more preferably 0.0001to 800 g/10 min, and has an intrinsic viscosity [η], as measured indecahydronaphthalene at 135° C., of usually 0.01 to 10 dl/g, preferably0.05 to 10 dl/g, more preferably 0.1 to 10 dl/g.

In an endothermic curve of the propylene polymer composition of thepresent invention measured by a differential scanning calorimeter (DSC),a maximum peak of a melting point (Tm, ° C.) is present at not lowerthan 100° C., and its quantity of heat of fusion is in the range ofpreferably 5 to 40 J/g, more preferably 5 to 35 J/g.

The highest endothermic peak (melting point) of the propylene polymercomposition of the present invention is not lower than 130° C.,preferably not lower than 140° C., more preferably not lower than 160°C.

The propylene polymer composition of the present invention has a melttension (MT) of usually 0.5 to 10 g, preferably 1 to 10 g, and thiscomposition is excellent in moldability such as film or tubemoldability. The melt tension (MT) is determined as a tension that isapplied to a filament when a strand extruded under the conditions of ameasuring temperature of 200° C. and an extrusion rate of 15 mm/min istaken off at a constant rate (10 m/min), and is measured by a melttension tester (manufactured by Toyo Seiki Seisaku-sho Ltd.).

Preparation of Propylene Polymer Composition

The propylene polymer composition can be prepared by various processespublicly known using the above components in the above amounts. Forexample, a multi-step polymerization process, a mixing process using aHenschel mixer, a V-blender, a ribbon blender, a tumbling blender or thelike, and a process comprising mixing, then melt kneading using asingle-screw extruder, a twin-screw extruder, a kneader, a Banbury mixeror the like, and granulation or pulverization are adoptable.

In the isotactic propylene copolymer composition of the presentinvention, additives, such as weathering stabilizer, heat stabilizer,anti-static agent, anti-slip agent, anti-blocking agent, anti-foggingagent, lubricant, pigment, dye, plasticizer, anti-aging agent,hydrochloric acid absorbing agent and antioxidant, may be added whenneeded, within limits not prejudicial to the objects of the presentinvention. Further, “other copolymers” (elastomers) described below indetail may be added within limits not prejudicial to the objects of thepresent invention, without departing from the subject matter of thepresent invention.

Other Copolymers

In the propylene polymer composition of the present invention, “othercopolymers” (elastmers, elastomeric resins) may be contained whenneeded.

Examples of the “other copolymers” include an ethylene/α-olefin randomcopolymer (iii), an ethylene/diene copolymer (iv) and an ethylene/trienecopolymer (v). The copolymers are used singly or in combination of twoor more kinds.

These “other copolymers” may be contained in amounts of usually 0 to 30parts by weight, preferably 0 to 20 parts by weight, based on 100 partsby weight of the isotactic polypropylene polymer of the presentinvention. When these copolymers are used in such amounts, a compositioncapable of producing a molded product having a good balance offlexibility, transparency and low-temperature impact resistance isobtained.

Ethylene/α-olefin Random Copolymer (iii)

As the ethylene/α-olefin random copolymer (iii) for use in the presentinvention, a soft ethylene/α-olefin copolymer having a density of notless than 0.860 g/cm³ and less than 0.895 g/cm³, preferably 0.860 to0.890 g/cm³, and having a melt flow rate (MFR, ASTM D 1238, 190° C.,load of 2.16 kg) of 0.5 to 30 g/10 min, preferably 1 to 20 g/10 min, isdesirable.

Examples of the α-olefins to be copolymerized with ethylene includeα-olefins of 3 to 20 carbon atoms, such as propylene, 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,1-undecene, 1-dodecene, 1-hexadecene, 1-octadence, 1-nonadecne,1-eicosene and 4-methyl-1-pentene. Of these, α-olefins of 3 to 10 carbonatoms are preferable. These α-olefins are used singly or in combinationof two or more kinds.

The ethylene/α-olefin random copolymer (iii) desirably contains unitsderived from ethylene in amounts of 60 to 90% by mol and units derivedfrom the α-olefin of 3 to 20 carbon atoms in amounts of 10 to 40% bymol.

The ethylene/α-olefin random copolymer (iii) may further contain unitsderived from other polymerizable monomers in addition to the aboveunits, within limits not prejudicial to the objects of the presentinvention.

Examples of the other polymerizable monomers include:

vinyl compounds, such as styrene, vinylcyclopentene, vinylcyclohexaneand vinylnorbonane;

vinyl esters, such as vinyl acetate;

unsaturated organic acids, such as maleic anhydride or theirderivatives;

conjugated dienes, such as butadiene, isoprene, pentadiene and2,3-dimethylbutadiene; and

non-conjugated polyenes, such as 1,4-hexadiene, 1,6-octadiene,2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene,dicyclopentadiene, cyclohexadiene, dicyclooctadiene,methylenenorbornene, 5-vinylnorbornene, 5-ethylidene-2-norbornene,5-methylene-2-norbornene, 5-isopropylidene-2-norbornene,6-chloromethyl-5-isopropenyl-2-norbornene,2,3-diisopropylidene-5-norbornene,2-ethylidene-3-isopropylidene-5-norbornene and2-propenyl-2,2-norbornadiene.

In the ethylene/α-olefin random copolymer (iii), units derived from theabove-mentioned other polymerizable monomers may be contained in amountsof not more than 10% by mol, preferably not more than 5% by mol, morepreferably not more than 3% by mol.

Examples of the ethylene/α-olefin random copolymers (iii) include anethylene propylene random copolymer, an ethylene/1-butene randomcopolymer, an ethylene/propylene/1-butene random copolymer, anethylene/propylene/ethylidenenorbornene random copolymer, anethylene/1-hexene random copolymer and an ethylene/1-octene randomcopolymer. Of these, an ethylene/propylene random copolymer, anethylene/1-butene random copolymer, an ethylene/1-hexene randomcopolymer and an ethylene/1-octene random copolymer are particularlypreferably used. These copolymers may be used in combination of two ormore kinds.

The ethylene/α-olefin random copolymer (iii) for use in the presentinvention has a crystallinity, as measured by X-ray diffractometry, ofnot more than 40%, preferably 0 to 39%, more preferably 0 to 35%.

The ethylene/α-olefin random copolymer can be prepared by a hithertoknown process using a vanadium catalyst, a titanium catalyst, ametallocene-catalyst or the like.

In the isotactic polypropylene composition, the ethylene/α-olefin randomcopolymer (iii) may be contained in an amount of usually 0 to 40% byweight, preferably 0 to 35% by weight. When the ethylene/α-olefin randomcopolymer (iii) is used in such an amount, a composition capable ofproducing a molded product having a good balance of rigidity, hardness,transparency and impact resistance is obtained.

Ethylene/diene Copolymer (iv)

The ethylene/diene copolymer (iv) used as an elastomer in the presentinvention is a random copolymer of ethylene and diene.

Examples of the dienes to be copolymerized with ethylene include:

non-conjugated dienes, such as dicyclopentadiene, 1,4-hexadiene,cyclooctadiene, methylenenorbornene and ethylidenenorbornene; and

conjugated dienes, such as butadiene and isoprene.

Of these, butadiene and isoprene are preferable. These dienes are usedsingly or in combination of two or more kinds.

In the ethylene/diene copolymer (iv) for use in the present invention,the content of units derived from the diene is desirable to be in therange of usually 0.1 to 30% by mol, preferably 0.1 to 20% by mol, morepreferably 0.5 to 15% by mol. The ethylene/diene copolymer (iv)desirably has an iodine value of usually 1 to 150, preferably 1 to 100,more preferably 1 to 50. Further, the ethylene/diene copolymer (iv)desirably has an intrinsic viscosity [η], as measured indecahydronaphthalene at 135° C., of 0.01 to 10 dl/g, preferably 0.05 to10 dl/g, more preferably 0.1 to 10 dl/g. The ethylene/diene copolymer(iv) can be prepared by a hitherto known process.

In the isotactic polypropylene composition, the ethylene/diene copolymer(iv) may be contained in an amount of usually 0 to 40% by weight,preferably 0 to 35% by weight. When the ethylene/diene copolymer (iv) isused in such an amount, a composition capable of producing a moldedproduct having a good balance of rigidity, hardness, transparency andimpact resistance is obtained.

Ethylene/triene Copolymer (v)

The ethylene/triene copolymer (v) used as an elastomer in the presentinvention is a random copolymer of ethylene and triene.

Examples of the trienes to be copolymerized with ethylene include:

non-conjugated trienes, such as 6,10-dimethyl-1,5,9-undecatriene,4,8-dimethyl-1,4,8-decatriene, 5,9-dimethyl-1,4,8-decatriene,6,9-dimethyl-1,5,8-decatriene, 6,8,9-trimethyl-1,5,8-decatriene,6-ethyl-10-methyl-1,5,9-undecatriene, 4-ethylidene-1,6-octadiene,7-methyl-4-ethylidene-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene(EMND), 7-methyl-4-ethylidene-1,6-nonadiene,7-ethyl-4-ethylidene-1,6-nonadiene,6,7-dimethyl-4-ethylidene-1,6-octadiene,6,7-dimethyl-4-ethylidene-1,6-nonadiene, 4-ethylidene-1,6-decadiene,7-methyl-4-ethylidene-1,6-decadiene,7-methyl-6-propyl-4-ethylidene-1,6-octadiene,4-ethylidene-1,7-nonadiene, 8-methyl-4-ethylidene-1,7-nonadiene and4-ethylidene-1,7-undecadiene; and

conjugated trienes, such as 1,3,5-hexatriene.

These trienes can be used singly or in combination or two or more kinds.

The above trienes can be prepared by hitherto known processes describedin, for example, EPO691354A1 and WO96/20150.

In the ethylene/triene copolymer (v) for use in the present invention,the content of units derived from the triene is desirable to be in therange of usually 0.1 to 30% by mol, preferably 0.1 to 20% by mol, morepreferably 0.5 to 15% by mol. The ethylene/triene copolymer (v)desirably has an iodine value of usually 1 to 200, preferably 1 to 100,more preferably 1 to 50.

Further, the ethylene/triene copolymer (v) desirably has an intrinsicviscosity [η], as measured in decahydronaphthalene at 135° C., of 0.01to 10 dl/g, preferably 0.05 to 10 dl/g, more preferably 0.1 to 10 dl/g.

The ethylene/triene copolymer (v) can be prepared by a hitherto knownprocess.

In the isotactic polypropylene composition, the ethylene/trienecopolymer (v) may be contained in an amount of usually 0 to 40% byweight, preferably 0 to 35% by weight. When the ethylene/trienecopolymer (v) is used in such an amount, a composition capable ofproducing a molded product having a good balance of rigidity, hardness,transparency and impact resistance is obtained.

In the propylene polymer composition of the present invention, asoftener (vi) and an inorganic filler (vii) can be used when needed.Examples of the softeners (vi) include petroleum type substances, suchas process oil, lubricating oil, paraffin, liquid paraffin, petroleumasphalt and vaseline; coal tars, such as coal tar and coal tar pitch;fatty oils, such as castor oil, linseed oil, rapeseed oil, soybean oiland coconut oil; waxes, such as tall oil, beeswax, carnauba wax andlanolin; fatty acids or their metal salts, such as ricinolic acid,palmitic acid, stearic acid, barium stearate and calcium stearate;synthetic high-molecular materials, such as petroleum resin,coumarone-indene resin and atactic polypropylene; ester typeplasticizers, such as dioctyl phthalate, dioctyl adipate and dioctylsebacate; and others, such as microcrystalline wax, factice, liquidpolybutadiene, modified-liquid polybutadiene and liquid Thiokol.

In the present invention, the softener (vi) is used in an amount of notmore than 200 parts by weight, preferably 2 to 100 parts by weight,based on the total 100 parts by weight of the isotactic polypropylene(i) and the propylene/ethylene/α-olefin copolymer (ii). If the amount ofthe softener (vi) used in the present invention exceeds 200 parts byweight, heat resistance and heat aging resistance of the resultingthermoplastic elastomer composition tend to be lowered.

Examples of the inorganic fillers (vii) which may be used in the presentinvention when needed include calcium carbonate, calcium silicate, clay,kaolin, talc, silica, diatomaceous earth, mica powder, asbestos,alumina, barium sulfate, aluminum sulfate, calcium sulfate, basicmagnesium carbonate, molybdenum disulfide, graphite, glass fiber, glassbead, Shirasu balloon, calcium hydroxide and aluminum hydroxide.

In the present invention, the inorganic filler (vii) is used in anamount of not more than 200 parts by weight, preferably 2 to 200 partsby weight, based on the total 100 parts by weight of the isotacticpolypropylene (i) and the propylene/ethylene/α-olefin copolymer (ii). Ifthe amount of the inorganic filler (vii) used in the present inventionexceeds 200 parts by weight, rubber elasticity and moldingprocessability of the resulting thermoplastic elastomer composition tendto be lowered.

Molded Product Comprising Propylene Polymer Composition

The propylene polymer composition of the present invention can be widelyapplied to hitherto known uses of polyolefins. In particular, thepolyolefin composition can be used by molding it into, for example,sheets, unstretched or stretched films, filaments and molded products ofother various forms. The molded product comprising the propylene polymercomposition of the present invention may be a multilayer laminate. Themultilayer laminate has at least one layer containing the propylenepolymer composition, and examples of such laminates include a multilayerfilm, a multilayer sheet, a multilayer container, a multilayer tube anda multilayer coating laminate contained as a constituent unit of a waterpaint.

Examples of the molded products include those obtained by thermoformingmethods publicly known, such as extrusion molding, injection molding,inflation molding, blow molding, extrusion blow molding, injection blowmolding, press molding, vacuum molding, calender molding and foammolding. The molded product is described with reference to the followingsome examples.

In the case where the molded product of the present invention is anextrusion molded product, its form or type is not specificallyrestricted. For example, there can be mentioned sheet, film(unstretched), pipe, hose, wire coating and tube. In particular, sheet(skin material), film, tube, catheter, monofilament (nonwoven fabric)and the like are preferable.

For extrusion molding of the propylene polymer composition, hithertoknown extrusion apparatuses and molding conditions are adoptable. Forexample, by the use of a single-screw extruder, a kneading extruder, aram extruder or a gear extruder, a molten propylene polymer compositionis extruded from a specific die, whereby the composition can be moldedinto a desired form.

A stretched film can be obtained by stretching such an extruded sheet oran extruded film (unstretched) as mentioned above by a publicly knownstretching method, such as tentering (lengthwise-crosswise stretching,crosswise-lengthwise stretching), simultaneous biaxial orientation ormonoaxial stretching.

When the sheet or the unsretched film is stretched, the stretch ratio isin the range of usually about 20 to 70 times in case of biaxialorientation, and is in the range of usually about 2 to 10 times in caseof monoaxial stretching. It is desirable to obtain a stretched filmhaving a thickness of about 5 to 200 μm by stretching.

As the molded product in the form of a film, an inflation film may beproduced. In the inflation molding, drawdown hardly takes place.

The molded product in the form of a sheet or a film comprising thepropylene polymer composition of the present invention is hardlyelectrostatically charged and is excellent in rigidity (e.g., tensilemodulus), heat resistance, stretchability, impact resistance, agingresistance, transparency, see-throuqh properties, gloss, moistureresistance and gas barrier properties, so that it can be widely used asa packaging film or the like. In this case, the molded product in theform of a sheet or a film comprising the propylene polymer compositionmay be a multilayer molded product, and the multilayer molded producthas at least one layer of the propylene polymer composition.

A molded product in the form of a filament can be produced by, forexample, extruding a molten propylene polymer composition through aspinneret. More specifically, a spanbond method or a meltblown method ispreferably employed. The filament thus obtained may be furtherstretched. This stretching has only to be performed to such an extentthat molecules are oriented at least monoaxially, and the stretching isdesirably carried out in a stretch ratio of usually 5 to 10 times. Thefilament comprising the propylene polymer composition of the presentinvention is hardly electrostatically charged and is excellent intransparency, rigidity, heat resistance, impact resistance andstretchability.

An injection molded product can be produced by injection molding thepropylene polymer composition into any of various forms using a hithertoknown injection molding apparatus and adopting the publicly knownconditions. The injection molded product comprising the propylenepolymer composition of the present invention is hardly electrostatiallycharged and is excellent in transparency, rigidity, heat resistance,impact resistance, surface gloss, chemical resistance, abrasionresistance and the like, so that it can be widely used as automotiveinterior trim, automotive exterior trim, housing of household electricappliances, container or the like.

A blow molded product can be produced by blow molding the propylenepolymer composition using a hitherto known blow molding apparatus andadopting the publicly known conditions. In this case, the blow moldedproduct comprising the propylene polymer composition may be a multilayermolded product, and the multilayer molded product has at least one layerof the propylene polymer composition.

For example, in the extrusion blow molding, the propylene polymercomposition in a molten state is extruded from a die at a resintemperature of 100° C. to 300° C. to form a tubular parison, then theparison is held in a mold of a desired shape, then air is blown, and theparison is fitted to the mold at a resin temperature of 130° C. to 300°C., whereby a hollow molded product can be produced. The stretch (blow)ratio is desirably in the range of 1.5 to 5 times in the crosswisedirection.

In the injection blow molding, the propylene polymer composition isinjected into a parison mold at a resin temperature of 100° C. to 300°C. to form a parison, then the parison is held in a mold of a desiredshape, then air is blown, and the parison is fitted to the mold at aresin temperature of 120° C. to 300° C., whereby a hollow molded productcan be produced. The stretch (blow) ratio is desirably in the range of1.1 to 1.8 times in the lengthwise direction and in the range of 1.3 to2.5 times in the crosswise direction.

The blow molded product comprising the propylene polymer composition ofthe present invention is excellent not only in transparency,flexibility, heat resistance and impact resistance but also in moistureresistance.

A press molded product is, for example, a mold stamping molded product.In the case where a substrate and a skin material are produced by pressmolding at the same time, i.e., composite integral molding (moldstamping molding), this substrate can be formed from the propylenepolymer composition of the present invention.

Examples of the mold stamping molded products include automotiveinterior trim, such as door trim, rear package trim, seat back garnishand instrument panel.

The press molded product comprising the propylene polymer composition ofthe present invention is hardly electrostatically charged and isexcellent in flexibility, heat resistance, transparency, impactresistance, aging resistance, surface gloss, chemical resistance,abrasion resistance and the like.

EFFECT OF THE INVENTION

According to the present invention, a propylene polymer compositioncapable of producing a molded product having excellent transparency,impact resistance, flexibility, heat resistance, scratch resistance andrubber elasticity with a good balance is obtained.

EXAMPLES

The present invention is further described with reference to thefollowing examples, but it should be construed that the invention is inno way limited to those examples.

Conditions of physical property tests, etc. are described below.

Measurement of Dynamic Viscoelasticity

Dynamic viscoelasticity was measured in a torsion mode of a width of 10mm and a length of 38 mm at 10 rad/s and a heating rate of 2° C./min inthe temperature range of −100° C. to 100° C. by the use of RDS-IImanufactured by Rheometric Scientific Inc., to obtain a loss tangent tanδ and a storage elastic modulus G′ at each temperature.

Tensile Test

Residual Strain

A load was applied to a dumbbell specimen having a shape of a length of50 mm, a length (LO) between marked lines of 30 mm, a width of 5 mm anda thickness of 1 mm^(t) under the conditions of a chuck distance of 30mm and a pulling rate of 30 mm/min to give a 100% strain (chuckdistance: 60 mm) to the specimen. The specimen was held in this statefor 10 minutes and then unloaded (free of load), and after the lapse of10 minutes from unloading, a length (L) between marked lines wasmeasured.Residual strain (%)=[(L−LO)/LO]×100

Tensile Modulus and M100 (Tensile Stress at 100% Strain)

Tensile modulus and M100 were measured using a JIS No. 3 dumbbell inaccordance with JIS K 6301 under the conditions of a span of 30 mm, apulling rate of 30 mm/min and a temperature of 23° C.

Penetration Temperature (° C.)

In this measurement, a test piece having a thickness of 1 mm was used,and a pressure of 2 kg/cm² was applied to a flat surface penetratorhaving a diameter of 1.8 mm at a heating rate of 5° C./min in accordancewith JIS K7196 to obtain a TMA curve. From the TMA curve, a penetrationtemperature (° C.) was determined.

Haze

Using a test piece having a thickness of 1 mm, haze was measured by adigital haze meter “NDH-20D” manufactured by Nippon Denshoku IndustriesCo., Ltd.

Abrasion Resistance Test

A test piece having a thickness of 2 mm was abraded with a SUS abrasionindenter (470 g) of 45R, a tip of which had been covered with cottoncanvas of #10, under the conditions of a temperature of 23° C., a numberof reciprocation times of 100, a reciprocation rate of 33 times/min anda stroke of 100 mm by the use of a Gakushin abrasion tester manufacturedby Toyo Seiki Seisaku-sho Ltd., and a change of gloss (ΔGloss) after theabrasion was determined as follows.ΔGloss=(Gloss before abrasion−Gloss after abrasion)/Gloss beforeabrasion×100Melting Point (Tm) and Glass Transition Temperature (Tg)

An endothermic curve of DSC was determined, and the temperature at theposition of a maximum peak was taken as Tm. In this measurement, asample was placed in an aluminum pan, heated up to 200° C. at 100°C./min, kept at 200° C. for 10 minutes, cooled down to −150° C. at 10°C./min and heated at 10° C./min to obtain an endothermic curve. From theendothermic curve, Tm was determined.

Intrinsic Viscosity [η]

Intrinsic viscosity was measured in decalin at 135° C.

Mw/Mn

Mw/Mn was measured in an orthodichlorobenzene solvent at 140° C. bymeans of GPC (gel permeation chromatography).

Synthesis Example 1 Synthesis of propylene/ethylene/butene Copolymer(ii-1)

In a 2000 ml polymerization apparatus having been thoroughly purged withnitrogen, 917 ml of dry hexane, 85 g of 1-butene and triisobutylaluminum(1.0 mmol) were placed at room temperature. The temperature in thepolymerization apparatus was raised to 65° C., and the system waspressurized to 0.77 MPa with propylene. Thereafter, the pressure in thesystem was adjusted to 0.78 MPa with ethylene. Subsequently, a toluenesolution in which 0.002 mmol ofdimethylmethylene(3-tert-butyl-5-methylcyclopentadienyl)fluorenylzirconiumdichloride and 0.6 mmol (in terms of aluminum) of methylaluminoxane(available from Tosoh Finechem Corporation) were contacted with eachother was introduced into the polymerization apparatus. With maintainingthe internal temperature at 65° C. and the internal pressure at 0.78 MPawith ethylene, polymerization was performed for 20 minutes, and then 20ml of methanol was added to terminate the polymerization. After thepressure was released, a polymer was precipitated from thepolymerization solution in 2 liters of methanol and then dried undervacuum at 130° C. for 12 hours. The amount of the polymer obtained was60.4 g, and the polymer had an intrinsic viscosity [η] of 1.81 dl/g, aglass transition temperature Tg of −27° C., an ethylene content of 13%by mol, a butene content of 19% by mol and a molecular weightdistribution (Mw/Mn), as measured by GPC, of 2.4. As for the quantity ofheat of fusion in the measurement by DSC, a clear peak of fusion was notconfirmed.

Synthesis Example 2 Synthesis of propylene/ethylene/butene Copolymer(ii-2)

In a 2000 ml polymerization apparatus having been thoroughly purged withnitrogen, 833 ml of dry hexane, 200 g of 1-butene andtriisobutylaluminum (1.0 mmol) were placed at room temperature. Thetemperature in the polymerization apparatus was raised to 40° C., andthe system was pressurized to 0.77 MPa with propylene. Thereafter, thepressure in the system was adjusted to 0.8 MPa with ethylene.Subsequently, a toluene solution in which 0.001 mmol ofdimethylmethylene(3-tert-butyl-5-methylcyclopentadienyl)fluorenylzirconiumdichloride and 0.3 mmol (in terms of aluminum) of methylaluminoxane(available from Tosoh Finechem Corporation) were contacted with eachother was introduced into the polymerization apparatus. With maintainingthe internal temperature at 40° C. and the internal pressure at 0.8 MPawith ethylene, polymerization was performed for 20 minutes, and then 20ml of methanol was added to terminate the polymerization. After thepressure was released, a polymer was precipitated from thepolymerization solution in 2 liters of methanol and then dried undervacuum at 130° C. for 12 hours. The amount of the polymer-obtained was41.4 g, and the polymer had an intrinsic viscosity [η] of 2.1 dl/g, aglass transition temperature Tg of −31° C., an ethylene content of 15%by mol, a butene content of 23% by mol and a molecular weightdistribution (Mw/Mn), as measured by GPC, of 2.1. As for the quantity ofheat of fusion in the measurement by DSC, a clear peak of fusion was notconfirmed.

Synthesis Example 3 Synthesis of propylene/ethylene/butene Copolymer(ii-3)

In a 2000 ml polymerization apparatus having been thoroughly purged withnitrogen, 833 ml of dry hexane, 100 g of 1-butene andtriisobutylaluminum (1.0 mmol) were placed at room temperature. Thetemperature in the polymerization apparatus was raised to 40° C., andthe system was pressurized to 0.76 MPa with propylene. Thereafter, thepressure in the system was adjusted to 0.8 MPa with ethylene.Subsequently, a toluene solution in which 0.001 mmol ofdimethylmethylene(3-tert-butyl-5-methylcyclopentadienyl)fluorenylzirconiumdichloride and 0.3 mmol (in terms of aluminum) of methylaluminoxane(available from Tosoh Finechem Corporation) were contacted with eachother was introduced into the polymerization apparatus. With maintainingthe internal temperature at 40° C. and the internal pressure at 0.8 MPawith ethylene, polymerization was performed for 20 minutes, and then 20ml of methanol was added to terminate the polymerization. After thepressure was released, a polymer was precipitated from thepolymerization solution in 2 liters of methanol and then dried undervacuum at 130° C. for 12 hours. The amount of the polymer obtained was36.4 g, and the polymer had an intrinsic viscosity [η] of 1.8 dl/g, aglass transition temperature Tg of −29° C., an ethylene content of 17%by mol, a butene content of 7% by mol and a molecular weightdistribution (Mw/Mn), as measured by GPC, of 2.1. As for the quantity ofheat of fusion in the measurement by DSC, a clear peak of fusion was notconfirmed.

Synthesis Example 4 Synthesis of propylene/ethylene/butene Copolymer(ii-4)

In a 2000 ml polymerization apparatus having been thoroughly purged withnitrogen, 917 ml of dry hexane, 50 g of 1-butene and triisobutylaluminum(1.0 mmol) were placed at room temperature. The temperature in thepolymerization apparatus was raised to 65° C., and the system waspressurized to 0.77 MPa with propylene. Thereafter, the pressure in thesystem was adjusted to 0.78 MPa with ethylene. Subsequently, a toluenesolution in which 0.002 mmol ofdimethylmethylene(3-tert-butyl-5-methylcyclopentadienyl)fluorenylzirconiumdichloride and 0.6 mmol (in terms of aluminum) of methylaluminoxane(available from Tosoh Finechem Corporation) were contacted with eachother was introduced into the polymerization apparatus. With maintainingthe internal temperature at 40° C. and the internal pressure at 0.78 MPawith ethylene, polymerization was performed for 30 minutes, and then 20ml of methanol was added to terminate the polymerization. After thepressure was released, a polymer was precipitated from thepolymerization solution in 2 liters of methanol and then dried undervacuum at 130° C. for 12 hours. The amount of the polymer obtained was46.4 g, and the polymer had an intrinsic viscosity [η] of 1.51 dl/g, aglass transition temperature Tg of −30° C., an ethylene content of 17%by mol, a butene content of 10% by mol and a molecular weightdistribution (Mw/Mn), as measured by GPC, of 2.1. As for the quantity ofheat of fusion in the measurement by DSC, a clear peak of fusion was notconfirmed.

Synthesis Example 5 Synthesis of propylene/ethylene/butene Copolymer(ii-5)

In a 1.5-liter autoclave having been vacuum dried and purged withnitrogen, 675 ml of heptane was placed at room temperature.Subsequently, 0.3 ml of a toluene solution of triisobutylaluminum(abbreviated to TIBA hereinafter) of 1.0 mmol/ml was added so that theamount of the toluene solution in terms of aluminum atom might become0.3 mmol, then with stirring, 28.5 liters of propylene (25° C., 1 atm)and 5 liters of 1-butene (25° C., 1 atm) were added, and the temperaturewas raised to reach 60° C. Thereafter, the system was pressurized to 6.0kg/cm²G with ethylene, and 7.5 ml of a toluene solution ofrac-dimethylsilylene-bis(2-methyl-4-phenyl-1-indenyl)zirconiumdichloride (0.0001 mmol/ml) synthesized by a publicly known process and2.3 ml of a toluene solution oftriphenylcarbeniumtetra(pentafluorophenyl)borate (0.001 mmol/ml) wereadded to initiate copolymerization of propylene, ethylene and 1-butene.As the catalyst concentration, the concentration ofrac-dimethylsilylene-bis(2-methyl-4-phenyl-1-indenyl)zirconiumdichloride was 0.001 mmol/l based on the whole system, and theconcentration of triphenylcarbeniumtetra(pentafluorophenyl)borate was0.003 mmol/l based on the whole system.

During the polymerization, ethylene was continuously fed to maintain theinternal pressure at 6.0 kg/cm²G. After 15 minutes from initiation ofthe polymerization, methyl alcohol was added to terminate thepolymerization reaction. The polymer solution was subjected toprecipitation, then sufficiently washed with acetone and filtered toobtain solids (copolymer). The solids were dried at 130° C. and 350 mmHgfor 12 hours in a stream of nitrogen to obtain apropylene/butene/ethylene copolymer. The yield of thepropylene/butene/ethylene copolymer was 24 g, and the copolymer had [η]of 1.9 dl/g, a glass transition temperature Tg of −31° C., an ethylenecontent of 15% by mol, a butene content of 6% by mol and a molecularweight distribution (Mw/Mn), as measured by GPC, of 2.4. As for thequantity of heat of fusion in the measurement by DSC, a clear peak offusion was not confirmed.

Example 1

20 Parts by weight of Mitsui polypropylene (i-1) (B101, MFR=0.5, Tm=165°C.) and 80 parts by weight of the propylene/ethylene/butene copolymer(ii-1) obtained in Synthesis Example 1 were kneaded at 200° C. by meansof a twin-screw extruder to obtain a propylene polymer composition. Theresults are set forth in Tables 1 and 2.

Example 2

The procedure of Example 1 was repeated, except that thepropylene/butene/ethylene copolymer (ii-1) obtained in Synthesis Example1 was replaced with the propylene/ethylene/butene copolymer (ii-2)obtained in Synthesis Example 2. The results are set forth in Tables 1and 2.

Example 3

The procedure of Example 1 was repeated, except that the amount ofMitsui polypropylene (i-1) (B101, MFR=0.5, Tm=165° C.) was changed to 15parts by weight and the propylene/ethylene/butene copolymer (ii-1)obtained in Synthesis Example 1 was replaced with 85 parts by weight ofthe propylene/ethylene/butene copolymer (ii-3) obtained in SynthesisExample 3. The results are set forth in Tables 1 and 2.

Example 4

The procedure of Example 3 was repeated, except that the amount ofMitsui polypropylene (i-1) (B101, MFR=0.5, Tm=165° C.) was changed to 25parts by weight and the amount of the propylene/ethylene/butenecopolymer (ii-3) obtained in Synthesis Example 3 was changed to 75 partsby weight. The results are set forth in Tables 1 and 2.

Example 5

The procedure of Example 3 was repeated, except that thepropylene/ethylene/butene copolymer (ii-3) obtained in Synthesis Example3 was replaced with the propylene/ethylene/butene copolymer (ii-4)obtained in Synthesis Example 4. The results are set forth in Tables 1and 2.

Example 6

The procedure of Example 4 was repeated, except that thepropylene/ethylene/butene copolymer (ii-3) obtained in Synthesis Example3 was replaced with the propylene/ethylene/butene copolymer (ii-4)obtained in Synthesis Example 4. The results are set forth in Tables 1and 2.

Comparative Example 1

The procedure of Example 1 was repeated, except that thepropylene/butene/ethylene copolymer (ii-1) obtained in Synthesis Example1 was replaced with Tafmer P (ii-6) (available from Mitsui Chemicals,Inc., ethylene/propylene copolymer, C2=80% by mol, [η]=2.5 dl/g). Theresults are set forth in Tables 1 and 2.

Comparative Example 2

40 Parts by weight of Mitsui polypropylene (i-1) (B101, MFR=0.5, Tm=165°C.) and 60 parts by weight of the propylene/ethylene/butene copolymer(ii-5) obtained in Synthesis Example 5 were kneaded at 200° C. by meansof a twin-screw extruder to obtain a propylene polymer composition. Theresults are set forth in Tables 1 and 2.

TABLE 1 Comp. Comp. Items Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 1 Ex.2 Isotactic polypropylene (i-1) MFR (g/10 min) = 20 20 15 25 15 25 20 400.5, Tm = 165° C., Mw/Mn = 5.5 Propylene/butene/ethylene randomcopolymer (ii-1) 80 [η] = 1.81, TB/{M100 × (Fp/100)^(0.5)} = 7.3,C2/C3/C4 (mol %) = 13/68/19 (mol %), M100 = 3.2 MPaPropylene/butene/ethylene random copolymer (ii-2) 80 [η] = 2.1, TB/{M100× (Fp/100)^(0.5)} = 1.8, C2/C3/C4 (mol %) = 15/62/23 (mol %), M100= 1.1MPa Propylene/butene/ethylene random copolymer (ii-3) 85 75 [η] = 1.8,TB/{M100 × (Fp/100)^(0.5)} = 2.3, C2/C3/C4 (mol %) = 17/76/7 (mol %),M100 = 0.9 MPa Propylene/butene/ethylene random copolymer (ii-4) 85 75[η] = 1.51, TB/{M100 × (Fp/100)^(0.5)} = 2.4, C2/C3/C4 (mol %) =17/73/10 (mol %), M100 = 1.0 MPa Propylene/butene/ethylene randomcopolymer (ii-5) 60 [η] = 1.9 TB/{M100 × (Fp/100)^(0.5)} = 5.4, C2/C3/C4(mol %) = 15/79/6 (mol %), M100 = 3.7 MPa Ethylene/propylene randomcopolymer (ii-6) 80 [η] = 2.5, C2/C3 (mol %) = 80/20 (mol %) Unit ofvalues in Table 1: % by weight

TABLE 2 Comp. Comp. Items Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 1 Ex.2 Dynamic viscoelasticity (A) Loss tangent tan δ peak (value, 0.6, 0.9,0.7, 0.6, 0.7, 0.6, 0.3, 0.5, temperature (° C.)) 14° C. 18° C. 17° C.16° C. 18° C. 16° C. 25° C. 18° C. (B) Storage elastic modulus ratio 3.83.5 2.5 3.1 3 3.1 5.1 4.2 (G′ (20° C.))/G′ (100° C.)) (C) Penetrationtemperature (° C.) 151 150 153 153 153 153 60 153 (D) Residual strain(%) 12 10 7 7 8 9 32 25 Tensile modulus (YM) (MPa) 25 19 17 31 17 28 2252 Transparency (haze) (%) 10 11 12 12 12 12 80 32 Abrasion resistance(ΔGloss) (%) 35 39 31 26 34 30 62 Unit of values in Table 2: % by weight

INDUSTRIAL APPLICABILITY

According to the present invention, a propylene polymer compositioncapable of producing a molded product having excellent transparency,impact resistance, flexibility, heat resistance, scratch resistance andrubber elasticity with a good balance is obtained.

According to the present invention, a molded product using a specificpropylene polymer composition exhibits excellent transparency, kinkresistance, flexibility, heat resistance, scratch resistance and rubberelasticity with a good balance, and sufficiently satisfies requirementsfor various uses.

1. A propylene polymer composition comprising 1 to 30 parts by weight ofisotactic polypropylene (i) having a melting point of not lower than150° C. and to 70 to 99 parts by weight of a copolymer (ii) whichcontains 45 to 80% by mol of a propylene component, 10 to 25% by mol ofan ethylene component, and optionally, 7 to 30% by mol a 1-butenecomponent, wherein the copolymer (ii) has a molecular weightdistribution (Mw/Mn) of not more than 4.0 as measured by gel permeationchromatography (GPC), and wherein the propylene polymer composition hasa tensile modulus (YM), as measured in accordance with JIS 6301, of notmore than 100 MPa, and a ratio of a storage elastic modulus G′ (20° C.)to a storage elastic modules G′ (100° C.) obtained from the dynamicviscoelasticity measurement, G′ (20° C.)/G′ (100° C.), of not more than5.
 2. The propylene polymer composition of claim 1, wherein thecopolymer (ii) further satisfies the following requirement: requirementwhen a melting point (Tm, ° C.) is present in an endothermic curvemeasured by a differential scanning calorimeter (DSC), the quantity ofheat of fusion ΔH is not more than 30 J/g, and a C3 content (% by mol)and the quantity of heat of fusion ΔH (J/g) satisfy the followingrelationship:ΔH <345 Ln (C3 content, % by mol)−1492, with the proviso that the C3content satisfies the condition of 76≦C3 content (% by mol)≦90.
 3. Thepropylene polymer composition as claimed in claim 1, wherein in anendothermic curve of the propylene polymer composition measured by adifferential scanning calorimeter (DSC), a maximum peak of a meltingpoint (Tm, ° C.) is present at not lower than 100° C., and a quantity ofheat of fusion of the proplylene polymer composition is in the range of5 to 40 J/g.
 4. The propylene polymer composition as claimed in claim 1,wherein a 1 mm sheet obtained by melt press molding of the propylenepolymer composition has a haze of not more than 30%.
 5. A propylenepolymer composition containing according to claim 1, that contains nostyrene or ethyene block copolymer and that satisfies, the followingrequirements (A), (B), (C) and (D) at the same time: (A) in a dynamicviscoelasticity measurement (10 rad/s) in a torsion mode, a peak of losstangent (tan δ) is present in the range of −25° C. to 25° C., and itsvalue is not less than 0.5, (B) a ratio of a storage elastic modulus G′(20° C.) to a storage elastic modulus G′ (100° C.) obtained from thedynamic viscoelasticity measurement, G′ (20° C.)/G′ (100° C.), is notmore than 5, (C) a penetration temperature (° C.), as measured inaccordance with JIS K7196, is in the range of 100° C. to 168° C., and(D) a residual strain measured after the lapse of 10 minutes fromunloading, said unloading being performed after a 100% strain is givenunder the conditions of a chuck distance of 30 mm and a pulling rate of30 mm/min and kept for 10 minutes, is not more than 20%.
 6. A moldedproduct comprising the propylene polymer composition of claim
 1. 7. Thepropylene polymer composition of claim 1, wherein the isotacticpolypropylene (i) is homopolypropylene.
 8. The propylene polymercomposition of claim 1, wherein the isotactic polypropylene (i) is apropylene/α-olefin random copolymer.
 9. The propylene polymercomposition of claim 8, wherein the propylene/α-olefin random copolymercomprises α-olefin selected from ethylene and α-olefins of 4 to 20carbon atoms.
 10. The propylene polymer composition of claim 9, whereinthe propylene/α-olefin random copolymer contains said α-olefin in anamount of 0.3 to 7% by mol.
 11. The propylene polymer composition ofclaim 9, wherein the propylene/α-olefin random copolymer contains saidα-olefin in an amount of 0.3 to 5% by mol.
 12. The propylene polymercomposition of claim 1, wherein the copolymer (ii) contains 50 to 75% bymol of the propylene component.
 13. The propylene polymer composition ofclaim 1, wherein the copolymer (ii) contains 10 to 23% by mol of theethylene component.
 14. The propylene polymer composition of claim 1,wherein the copolymer (ii) contains 12 to 23% by mol of the ethylenecomponent.
 15. The propylene polymer composition of claim 1, wherein thecopolymer (ii) contains 7 to 25% by mol of the 1-butene component. 16.The propylene polymer composition of claim 1, wherein the copolymer (ii)contains 7 to 20% by mol of the 1-butene component.
 17. The propylenepolymer composition of claim 1, wherein the copolymer (ii) has acrystallinity, as measured by X-ray diffractometry, of not more than20%.
 18. The propylene polymer composition of claim 1, wherein thecopolymer (ii) has a molecular weight distribution (Mw/Mn), as measuredby gel permeation chromatography (GPC), of not more than 3.0.